Some of them get a bit better as they age and are less impaired as they learn some strategies. I didn't get a chance to see the kids I worked with when they were young bc I only saw them at the initial stage... infant/toddler and preschool level as a private therapist. And I had to help many of these parents through accepting their child's diagnosis. That was tough! I did not work in any school district. I switched between adults (nursing homes/rehab centers) and kids (some in rehab centers or home therapy for a change of pace.

I cannot say what happens to many of them but I suspect their parents are still engaged with them no matter what age they are. There are institutions only for the most severe. We had "flesh eaters" In a local state facitlity where I used to live. They had to wear helmets with special mouth guards so they wouldn't eat their own fingers due to sensory issues, etc.

My own sister has a son on the high end of the spectrum who attempted to commit suicide several times in the past. So they have treated him with kid gloves. He also has Tourettes and is socially inadequate along with great anxiety that keeps him from actually living normally. He completed a college degree locally in computer science. Had a brief job after he graduated at a government contracting agency fixing computers for a couple of years. His older brother helped him get the job. Unfortunately, he was laid off the job when they cut back and has not been to work since. They have enabled him because he has threatened suicide and has severe panic attacks. He leaves a room if there is ANY confrontation at all. He cannot handle life. He plays computer games all day. He also has agrophobia I think as he hardly ever leaves the home. He cleans and cooks and has taken care of my sister through her many surgeries for back etc. He is almost 30 now. Has no health insurance. And they have told their other 4 kids that whoever takes care of him when they are gone will be given the bulk of their estate. So far his younger sister said she will do so. It is very sad to see him a very attractive young man waste his life in his parents home that way. If he were my kid this would NOT have happened to him. I would have made sure he was out and about some way and independent.